Bacteria is found virtually everywhere and is responsible for a significant amount of disease and infection. Ridding surfaces of bacteria is desirable to reduce human exposure. Bacteria in normal environments have developed self preservation mechanisms and are therefore extremely difficult to remove and/or eradicate.
Bacteria can be found in both planktonic and biofilm forms. In the biofilm form, they interact with surfaces and form surface colonies which adhere to a surface and continue to grow. The bacteria produce exopolysaccharide (EPS) and/or extracellularpoly-saccharide (ECPS) macromolecules that keep them attached to the surface and form a protective film that is effective against many forms of attack. Protection most likely can be attributed to the small diameter of the flow channels in the matrix, which restricts the size of molecules that can transport to the underlying bacteria, and consumption of biocides through interactions with portions of the EPS/ECPS macromolecular matrix.
Additionally, the bacteria in biofilm form are down-regulated (sessile) and not actively dividing. This makes them resistant to attack by a large group of antibiotics and antimicrobials, which attack the bacteria during the active parts of their lifecycle, e.g., cell division.
Due to the protection afforded by the macromolecular matrix and their down-regulated state, bacteria in a biofilm are very difficult to treat. The types of biocides and antimicrobials that are effective in treating bacteria in this form are strongly acidic, oxidizing, and toxic, often involving halogen atoms, oxygen atoms, or both. Common examples include concentrated bleach, strong mineral acids (e.g., HCl) and hydrogen peroxide. Commonly, large dosages of such chemicals are allowed to contact the biofilm for extended amounts of time (up to 24 hours in some circumstances), which makes them impractical for many applications.
Recent developments have involved formulations intended for use against compromised animal/human tissue which, accordingly, are intentionally gentle so as to prevent damage or irritation to compromised tissue. These formulations solvate the biofilm matrix so that still-living bacteria can be rinsed or otherwise removed from infected tissue. The concentrations of active ingredients in these formulations are too low to effectively kill the bacteria in the biofilm, and are thus ill suited for surface disinfection.
A solution that can disrupt the macromolecular matrix, or bypass and/or disable the defenses inherent in these matrices, allowing lethal doses of the antimicrobial ingredients in the solution to access and kill the bacteria in their biofilm and sessile states, remains desirable. Such a solution that is not particularly acidic or caustic (i.e., about 3≦pH≦9) and has little to no toxicity would be particularly advantageous.